Siccative metal salts and method of



I06. COMPOSITIONS,

COATING OR PLASTIC.

Patented Dec. 8, 1936 UNITED STATES Search Rec;

PATENT OFFICE SICCATIVE METAL SALTS AND METHOD OF USING THEM Herman A. Bruson, Elkins Park, and Otto Stein, Lansdownc, Pa., assignors to The Resinous Products & Chemical Company, Philadelphia,

No Drawing. ApplicationFebruary 26, 1935,

Serial No. 8,300. In Germany March 5, 1934 15 Claims.

the paint or varnish is constant, irrespective of.

the age of the material in which it is used.

Many salts of organic acids and the so called siccative metals such as lead, cobalt and mangar'is aie used for accelerating the drying of paints and varnishes among which are the salts of the naphthenic acids, of fatty acids, of rosin, etc., but on account of the limited solubility of such salts in paints and varnishes they are not entirely satisfactory. If successfully incorporated in paint or varnish, they tend to precipitate on standing. Furthermore, they are usually of a dark color which is imparted to the finished paint or varnish and this is a disadvantage particularly in the manufacture of white enamels and others of very delicate color.

It is an object of this invention to eliminate these disadvantages by using the complex polyvalent metal salts containing more than one acid radical. It is a further object to provide a method for the manufacture of these salts.

It has been pointed out above that the lead, cobalt and manganese salts of the naphthenic acids are soluble only to a limited degree in paints and varnishes and that they tend to precipitate on standing particularly in alkali refined oils of low acid-number. We have found that if instead of the straight naphthenates of these metals, a complex salt containing in addition to the naphthenate radical the radical of an alkoxy carboxylic acid is used, the solubility is greatly increased and the salts do not precipitate on long standing even in the alkali refined oils of low acid-number.

The alkoxy carboxylic or ether acids used in this invention are of the kind in part exemplified in United States Patents 1,920,137, 1,920,160 and 1,969,709, and in the copending application Ser. No. 588,499 filed January 23, 1932, now Patent No. 2,044,968 issued June 23, 1936. They have the general formula R/OCnH2nCoOH, in which R is a cycloaliphatic hydrocarbon radical or an aliphatic hydrocarbon radical containing at least five carbon atoms, CnHZn is a noncyclic alkylene group and n has a value of one, two or three.

As examples of these acids, the following may be mentioned:

Hexyloxyacetic acid, CsH1a-O-CH2CO H and its higher homologues such as the heptyl, octyl, or nonyloxyacetic acids, or cyclohexyloxyacetic acid.

Amyloxypropionic acid and its higher homologues such as the hexyl,

heptyl, cyclohexyl, or octyloxypropionic acids or the corresponding isopropionic acids.

Amyloxybutyric acid and its higher homologues such as the hexyl, heptyl, octyl, or cyclohexyloxybutyric acids or the corresponding isomeric acids, such as the alkoxyisobutyric acids.

In these ether acids the hydrocarbon radical R can be a straight or branched-chain alkyl group of more than 4 carbon atoms, and if hydroaromatic, it can also be a terpenic hydrocarbon radical such as fenchyl or bornyl.

The naphthenic acids used are the commercial grades of the kind obtained from Californian, Russian, Rumanian or other naphthenic petroleums, and should possess preferably an acid-number between 250"and 315 or thereabouts.

The term polyvalent metal as used herein includes the common divalent and trivalent metals but more particularly the group of so-called siccative metals principally cobalt, manganese and lead, which are the most important for the purpose of accelerating the drying of autoxidizable oils, paints, varnishes and similar resinous coating materials. Other polyvalent metal salts such as the zinc, calcium, cerium, copper, iron, vanadium, aluminum, mercury, chromium and nickel are of somewhat less importance as siccatives but are sometimes used in oleoresinous varnishes as hardening agents, resins or preservatives, and this invention is intended therefore to include these metals since the new complex salts herein described may be prepared from these polyvalent metals also.

The siccative metal salts described herein, as made by the present process, differ from those previously known, not only in their chemical constitution but also in their physical properties. They are for example, very much more soluble and stable in alkali-refined linseed oil, as well as in heat-bodied or air-blown linseed 011, than are the a; a r

corresponding well-known straight metal naphthenates. Furthermore, the new manganese salts are a very pale straw color instead of the characteristic red or dark brown of the manganese naphthenates which are at present known.

Chemically these new compounds represent complex metal salts in which it is believed that one valence of the polyvalent metal is bound to an ether acid radical and another valence of the metal is bound to a naphthenic acid radical. This appears to be the case since a simple mixture of the corresponding straight metal naphthenate and straight metal salt of the ether acid, has a different solubility in petroleum naphtha or in linseed oil than has the complex salt made from the same acids. For example, a mixture of equal mols of manganese naphthenate and manganese octyloxyacetate, behaves quite differently from the complex manganese naphthenic-octyloxyacetate made from the same molecular equivalents of the two acids by the process described herein. The simple physical mixture rapidly precipitates from alkali-refined linseed oil when added thereto (as a 3% solution in petroleum naphtha to give .015% Mn on the weight of the oil), whereas the complex salt, under the same conditions, does not.

The tendency of the simple polyvalent metal naphthenates to precipitate from low acid number linseed oil, and for solutions of such metal naphthenates in petroleum hydrocarbons to thicken on standing is already known. Numerous attempts to remedy this condition have been made in the past.

It has been proposed for instance, to prevent sedimentation and gelatinization of the naphthenates in petroleum hydrocarbons by adding thereto protective agents of the nature of free carboxylic acids of the unsaturated fatty series or free aromatic acids (U. S. Pat. 1,895,200). The products thus obtained are, however, mixtures of naphthenate with free acid. When added cold to alkali-refined linseed oils the manganese and cobalt salts of naphthenic acids tend to precipitate rapidly on standing; and the color of the manganese salts is dark reddish brown. The same is true of products made by fusing metal naphthenates with drying oilfatty acids (U. S. Pat. 1,916,805) or with rosin and of products made by heating polyvalent metal oxides, hydroxides, carbonates, or acetates with naphthenic and benzoic or linseed oil acids. Other methods involve adding alcohols such as butanol to the naphthenate solutions to prevent undesirable precipitations from solution.

By the present process however, all of these faults and disadvantages are eliminated, and complex naphthenate-alkoxyacetate salts of a high degree of solubility and stability in drying oils and petroleum naphthas are obtained.

In accordance with the present invention, a saturated monobasic ether acid of the general formula R-OCnH2n-COOH, wherein R is a cycloaliphatic hydrocarbon radical or an aliphatic hydrocarbon radical containing at least 5 carbon atoms and "n is a whole number of from 1 to 3 inclusive, is reacted in one step with an oxide, hydroxide, acetate, or carbonate of a polyvalent metal and a monobasic naphthenic acid; or alternatively, a water-soluble, inorganic acid salt of a polyvalent metal such as manganous chloride or cobaltous sulfate is reacted with an alkali metal acetate, carbonate, or hydroxide in the presence of an ether acid of the above type together with 'laphthenic acid, the reaction being carried out in an inert, volatile organic liquid which is preferably immiscible with water, and which is also a good solvent for the final complex salt. Such solvents as benzene, toluene and petroleum naphtha are suitable for the purpose.

The dried commercial oxides, hydroxides, and carbonates of some metals, notably manganese and cobalt react only very slowly below 130 C. with a mixture of naphthenic acid and the ether acids, whereas lead oxide (PbO), hydroxide, or carbonate reacts quite readily. In order, therefore, to prepare the cobalt and the manganese complex salts of these acids at a low temperature so as to prevent decomposition and discoloration of the complex salts, the present invention utilizes the hydroxides, carbonates and acetates of these polyvalent metals in what might be called the nascent state. In other words, the hydroxide, carbonate or acetate of the polyvalent metal is formed in the presence of the organic acids and reacts with them to form the complex salt before it has time to dehydrate or go over to a less reactive modification. This is accomplished by simply mixing a manganous or cobaltous salt of an inorganic acid, such as the chloride, nitrate or sulfate, with sodium or potassium hydroxide carbonate, or acetate together with the two different organic acids in the presence of an organic solvent. It is not necessary that water be present as the double decomposition of the manganous or cobaltous salt on the one hand, and the sodium or potassium compound on the other, takes place readily in benzol for example. The manganous or cobaltous hydroxide, carbonate, or acetate which forms, is immediately reacted upon by the two different organic acids present, and the complex manganous or cobaltous salt thus formed immediately dissolves in the organic solvent. These reactions take place readily below 100 C., preferably around -90 C. For best results the two acids are used in equimolecular proportions in an amount sufficient to completely combine with the metal of the salt used. The reaction can be completed by gentle heating at -110" C. with agitation and the moisture, or acetic acid present may be removed by distillation. The proportions, however, of the two acids may be varied within fairly wide limits, depending upon the nature of the acids used, and mixtures of more than one ether acid may be used. The naphthenic acids themselves are, of course, mixtures of a number of different acids, and the complex salts therefore contain necessarily mixtures of at least two different acid radicals.

The complex salts formed are filtered free from insoluble reaction products, while dispersed in the inert organic solvent, and the clear filtrate is evaporated to dryness in vacuo to deposit the dry solid complex salt as a resinous mass. The latter may be used directly as a siccative for printing inks, paints and varnishes or may be dispersed in petroleum naphtha or in linseed oil for use as a liquid drier in varnish R-OCH2-COOH in which R is an alkyl hydrocarbon group derived from the mixed monohydric primary and 75 I06. COMPOSITIONS,

COATING OR PLASTIC.

secondary branched chain alcohols of boiling range 157-196 C. resulting from the synthetic manufacture of methanol from carbon monoxide and hydrogen, as described in U. S. Pat. 1,920,137 (Example 1). This acid is a colorless oil boiling at 142-153 C./8 mm. and consists mainly of mixed octyloxyacetic acids, of acid number 290- 300. 250 grams of the above mixed alkoxyacetic acids are mixed with 300 grams of distilled naphthenic acid and 750 grams toluene. To the solution 269 grams of litharge is added and the mixture agitated for several hours, whereby most of the litharge dissolves. The solvent and water formed by the reaction are then distilled off. The residue is dissolved in petroleum naphtha and after filtration the clear filtrate is ready for use as a siccative for paints. When added as a siccative solution containing 20% lead (calculated as metal), to an alkali-refined linseed oil, or an air blown linseed oil, so that the percentage of metal is 1% on the weight of the oil, a clear pale solution is obtained at room temperature which does not precipitate even on long standing, whereas ordinary lead naphthenate or mixtures thereof with fatty or aromatic acids rapidly precipitates.

Example 2.-A mixture of 38 grams mixed octyloxyacetic acid as described above, and 45 grams of distilled naphthenic acid (water-white) in 200 grams of toluene was agitated with 40 grams of crystalline manganous chloride and 60 grams of sodium acetate crystals. After stirring for about one-half hour at room temperature, the manganous chloride crystals d sappeared. The mixture was then heated to drive off the water and acetic acid formed, together with some of the solvent. Steam was then passed in, to completely remove the last traces of acetic acid from the residue. The supernatant water layer was then decanted, the solvent evaporated and the residue dried in vacuo at about 100 C. The latter formed a very pale straw-colored resin containing about 10-11% manganese. Its solutions in petroleum naphtha are very stable and can be dissolved in alkali-refined linseed oil without subsequently precipitating out.

In place of the manganous chloride a molecularly equivalent amount of cobaltous chloride can be used. The cobalt salt thus obtained when anhydrous is a bluish violet resin containing about 11% cobalt.

The octyloxyacetic acid can be replaced by an equal weight of capryloxyacetic acid Eaample 3.A solution of 37.6 grams of di stilled naphthenic acid and 45 grams mixed octyloxyacetic acids of the kind set forth in Example 1, in 200 grams of toluene, is agitated with a mixture of 56.5 grams cobaltous sulfate crystals (CSO4-7H2O) and 22 grams dry sodium carbonate. After about one half hour stirring, the mixture is gradually warmed and the water formed, together with some toluene, distilled off during a period of about 1% hours. The toluene recovered is replaced and the solution subsequently filtered to remove the residue of sodium sulfate. Upon removal of the solvent, preferably under vacuum, a blue resinous mass is obtained containing 12% of cobalt in the form of the complex naphthenate-octyloxyacetate. Its solubility StdICI'I KOOITI in alkali-refined linseed oil is extremely high, as comparedwith cobalt naphthenate. The sodium carbonate can be replaced by a molecularly equivalent amount of sodium hydroxide.

In the above examples the alkoxyaliphatic acids used may be replaced mol for mol by any ofthe acids of the formula R-O-CnH2n-COOH as hereinabove described. We prefer, however, to employ the ether acids of the above type which possess carbon atoms such as cyclohexyloxybutyric acid, heptyloxypropionic acid, hexyloxybutyric acid, as these appear to give the highest solubility for the maximum metal content. I

Example 4.--A solution of 37.6 grams of alkoxyacetic acids of the kind set forth in Example 1, and 45.1 grams of distilled naphthenic acid of acid number 290, in 100 grams toluene was stirred with 100 com. Water and 40 grams manganous chloride crystals. To this mixture, 160 com. of a 10% aqueous sodium hydroxide solution was added. The temperature gradually rose to 40 C. After about one-half hour, the mixture was heated to boiling. The water together with the toluene was then distilled off and the residue taken up in toluene, filtered, and evaporated to dryness in vacuo. The purified product thus obtained was dissolved in 180 grams of petroleum naphtha for use as a liquid drier. When added to alkali-refined linseed oil, the siccative remains in solution, whereas a manganese salt similarly prepared from naphthenic acids alone is immediately precipitatad from the oil.

Example 5.-The following mixture was stirred and heated under a reflux condenser for one hour:

233 g. Rumanian naphthenic acids having an acid number of 240 180 g. beta-n-hexyloxybutyric acid boiling at 154-156 C. at 10 mm. Hg .600 g. toluol 285 g. cobalt sulphate CoS04-7H2O 81 g. sodium hydroxide 750 cc. water The water and solvent were then distilled off, the residue dissolved in toluol, filtered and the filtrate evaporated to dryness. The product is a bluish, resinous mass. The yield was 470 g. The product is soluble in petroleum benzine in all proportions and does not thicken nor form a precipitate on standing for a long time.

. In place of the hexyloxybutyric acid, 216 g. of beta-secondary-octyloxybutyric acid,

CHa*-(|3H-CH2COOH O-Cs-H17 boiling point, 165-168 C. at 9 mm. Hg, or 188 g. of beta-cyclo-hexyl-oxybutyric acid, boiling point 157-160" C. at 10 mm. Hg, may be used. Example 6.--The following mixture was heated for two hours at 50-60" 0.;

233 g. Rumanian naphthenic acids having an acid number of 240 188 g. beta-n-heptyloxypropionic acid 575 g. benzol 200 g. manganous chloride MnCl2-4H2O 113 g. potassium hydroxide 500 cc. water The mixture was then distilled to remove the benz'ol and the water. The residue was dissolved directly in one liter of petroleum benzine and filtered. The filtrate is an extremely stable solution of the siccative. o

In the above examples, soluble salts of any of the other polyvalent metals can be used in whole or in part to replace those described specifically. The reaction time, temperature and volume of solvent, can be adjusted to suit the nature of the salt and the size of the batch; the more viscous salts such as the aluminum or zinc salts requiring more solvent than those less viscous.

In employing the above salts as siccatives or driers for autoxidizable paints, oleoresinous varnishes, alkyd resins and similar coating or filmforming compositions, we prefer to add the lead, cobalt or manganese complex naphthenic alkoxyacetate to the autoxidizable composition so that the percentage of cobalt or manganese on the weight of the drying oil is from .015 to 0.30% and the percentage of lead is from 0.50% to about 1%. This addition can be made by adding the solid salt or a solution thereof to the drying oil compositions and stirring until uniformly dissolved. Upon evaporating such compositions as in the formalion of a varnish film, the rate of drying will be found to be greatly accelerated and the varnish itself, even when stored in cans for a year or more, will be found to be free from precipitated driers.

What we claim is:

l. A process for preparing a complex siccative metal salt readily soluble in low acid-number drying oils, which comprises heating a mixture of monobasic naphthenic acids and an ether acid of the general formula R-CnH2n-COOH wherein R is a member of the group consisting of cycloaliphatic hydrocarbon radicals and aliphatic hydrocarbon radicals containing at least five carbon atoms, and n is a whole number of from 1 to 3 inclusive, with one of the group consisting of the oxide, hydroxide, carbonate or acetate of a siccative metal, in the presence of a volatile, inert organic solvent for the complex salt.

2. A process for preparing a complex siccative salt readily soluble in low acid-number drying oils, which comprises heating a mixture of monobasic naphthenic acids and an ether acid of the general formula RO-CnHznCOOH wherein R is a member of the group consisting of cycloaliphatic hydrocarbon radicals and aliphatic hydrocarbon radicals containing at least five carbon atoms, and n is a whole number of from 1 to 3 inclusive, with a water-soluble, mineral acid salt of a siccative metal, and one of the group consisting of the acetate, hydroxide, and carbonate of an alkali metal, in the presence of an inert, volatile, water-immiscible organic solvent for the complex salt.

3. A process for preparing a complex manganese salt readily soluble in low acid-number drying oils, which comprises heating a mixture of approximately equimolecular proportions of naphthenic acid and octyloxyacetic acids, with a molecular equivalent of a water-soluble, mineral acid salt of manganese, and one of the group consisting of the acetate, hydroxide, and carbonate of an alkali metal, in the presence of a volatile, hydrocarbon solvent for the complex salt.

4. A process for preparing a complex cobalt salt readily soluble in low acid-number drying oils, which comprises heating a mixture of approximately equimolecular proportions of naphthenic acid and octyloxyacetic acids with a molecular equivalent of a water-soluble, mineral acid salt of cobalt, and one of the group consisting of the acetate, hydroxide, and carbonate of an alkali metal, in the presence of a volatile inert hydrocarbon solvent for the complex salt.

5. A process for preparing a complex lead salt readily soluble in low acid-number drying oils which comprises heating a mixture of approximately equimolecular proportions of naphthenic an octyloxyacetic acids with litharge in the presence of a volatile, inert organic solvent for the complex salt.

6. A complex salt of a siccative metal, a naphthenic acid, and a monobasic ether acid of the general formula ROCnH2n-COOH wherein R is a member of the group consisting of cycloaliphatic hydrocarbon radicals and aliphatic hydrocarbon radicals containing at least carbon atoms, and n is a whole number of from 1 to 3 inclusive, said salt being readily soluble in alkalirefined linseed oil.

7. A complex salt of a siccative metal, a naphthenic acid and a monobasic, non-aromatic ether acid having carbon atoms; said salt being readily soluble in alkali-refined linseed oil.

8. A complex salt of a siccative metal, a naphthenic acid and an octyloxyacetic acid, said salt being readily soluble in alkali-refined linseed oil.

9. A complex salt of a siccative metal, a naphthenic acid, and mixed ether acids of the general formula R,O--CH2-COOH wherein R is the alkyl radical of a branched chain, aliphatic, monohydric alcohol having more than 5 carbon atoms which is present in the mixture of byproduct alcohols resulting from the catalytic synthesis of methanol from carbon monoxide and hydrogen.

10. A complex salt constituted by a siccative metal in chemical combination with at least two acids, one of which is a naphthenic acid having an acid-number between about 250 and 315, and the other of which is an alkoxyacetic acid mixture, having a boiling range of 142-153 C./8 mm. said alkoxyacetic acid mixture being essentially mixed octyloxyacetic acids and having an acidnumber of about 290 to 300.

11. A complex salt constituted by one of the group consisting of cobalt, manganese, and lead, in chemical combination with two different acids, one of which is naphthenic and the other an alkoxyacetic acid mixture having an acid number of about 290 to 300 and containing at least 5 carbon atoms in the alkyl group.

12. In the process of accelerating the drying of autoxidizable film-forming compositions, the step comprising incorporating therewith, a complex siccative metal salt of a monobasic naphthenic acid and an ether acid of the formula RO--CnH2n-COOH, wherein R is a member of the group consisting of cycloaliphatic hydrocarbon radicals and aliphatic hydrocarbon radicals containing at least 5 carbon atoms and n is a whole number of from 1 to 3 inclusive; said complex salt having one valence of the metal satisfied with the naphthenic acid radical and another valence bound to the ether acid radical.

13. In the process of accelerating the drying of autoxidizable film-forming compositions, the step comprising incorporating therewith a complex lead salt of a monobasic naphthenic acid and an ether acid of the formula wherein R is a member of the group consisting of cycloaliphatic hydrocarbon radicals and aliphatic hydrocarbon radicals containing at least 5 carbon atoms and n is a whole number of from 1 to 3 inclusive; said complex salt having one valence of the metal satisfied with the naphthenic acid I06. COMPOSITIONS, v

COATING OR PLASTIC.

radical and another valence bound to the ether acid radical.

14. In the process of accelerating the drying of autoxidizable film-forming compositions, the step comprising incorporating therewith, a complex cobalt salt of a monobasic naphthenic acid and an ether acid of the formula wherein R is a member of the group consisting of cycloaliphatic hydrocarbon radicals and aliphatic hydrocarbon radicals containing at least 5 carbon atoms and n is a whole number of from 1 to 3 inclusive; said complex salt having one valence of the metal satisfied with the naphthenic acid radical and another valence bound to the ether acid radical.

Search Room 15. In the process of accelerating the drying of autoxidizable film-forming compositions, the step comprising incorporating therewith a complex manganese salt of a monobasic naphthenlc acid and an ether acid of the formula wherein R is a member of the group consisting of cycloaliphatic hydrocarbon radicals and aliphatic hydrocarbon radicals containing at least 5 carbon atoms and n is a whole number of from 1 to 3 inclusive; said complex salt having one valence of the metal satisfied with the naphthenic acid radical and another valence bound to the ether acid radical.

HERMAN A. BRUSON.

OTTO STEIN. 

